Regions Financial Corp. (RF) is exchanging stock valued at about $9.8 billion for hometown rival AmSouth Bancorporation (ASO) in a deal that would create one of the nation's biggest bank holding companies, it was announced Thursday.

The combined company under the deal that the companies described as a merger would have nearly $140 billion in assets, a market capitalization of about $26 billion and 2,000 branches in the South, Midwest and Texas. They said it would be the nation's 10th largest bank.

The new company will retain the Regions name, and Jackson W. Moore, chairman, president and chief executive of Regions, will be chairman.

C. Dowd Ritter, 58, chairman, president and chief executive of AmSouth, will be the president and chief executive officer of the combined company, which will maintain its headquarters in Birmingham where both companies are now based.

Regions will exchange 0.7974 of a share for each share of AmSouth common stock. Based on Wednesday's closing price of $35.53 for Regions, it is paying about $28.33 per share for AmSouth. That is about 2 percent less than its closing price of $28.90 on Wednesday.

Regions' shares rose 62 cents, or 1.8 percent, to $36.15 in morning trading on the New York Stock Exchange, while AmSouth gained 35 cents to $29.25 after rising to a new 52-week high of $29.83 earlier in the session. AmSouth traded at a 52-week low of $23.85 in October.

The companies said their boards would be combined, but did not say in the news release how large the new board would be or how many seats each side in the deal would have.

Regions has about $84.6 billion in assets and had a market capitalization as of Wednesday of about $16.2 billion, while AmSouth has total assets of $52.9 billion and a market capitalization of about $10 billion as of Wednesday.

The combined company expects to save about $400 million in costs, of which $150 million is expected to be realized in 2007. Additionally, the combined company expects to incur restructuring costs of approximately $700 million before taxes.